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Steam Reforming - Real Reformer Simulation Hysys

hysys reforming reformer simulation catalyst

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#1 A_D_M_MII

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Posted 15 September 2021 - 05:58 AM

Hi everyone,
 
I am doing a simulation of a steam reforming plant, the objective of this simulation is to achieve the real operation data of controllers and indicators.
 
I have already simulated this plant with the design data but like everyone knows the reality is more complex, however, this is my question:
 
How can i simulate the decrease of the catalyst activity?, i mean i have simulated the reformer reactor like a PFR with the kinetic equations, but it is a theoretical and experimental equation that doesn't take into account other parameters like the catalyst deactivation. 
 
In the other hand, my principal problem is that flue gas that goes to the convection zone has more temperature than the real temperature that is given by the indicator.
 
I have simulated it like a combustion adiabatic reactor (100% Conv), the product is a current of flue gas with high temperature that gives the "radiant energy" by a cooler to the reformer (PFR), at the exit of this cooler is supposed to be the temperature indicator.
 
I also have the feed (kg/h), the composition (% mol), temperature, and pressure of the inlet currents of the combustion reactor (Furnace).
 
I hope i was clear.
 
Thank you all!
 
ADM  :D

 



#2 Pilesar

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Posted 15 September 2021 - 07:44 AM

A few comments for consideration... 
Consider using equilibrium reactors instead of PFR. Adjust the approach to equilibrium to tune for catalyst performance. 
Are you adding excess air to your combustion? Extra air lowers flue gas temperature and affects the convection section heat transfer. The heat transfer to the reaction is in the balance also. An inaccurate heat of reaction might be affecting your results.
Including the convection section in the model will provide additional balances that have to be matched with the flue gas flow and temperatures. Adding these additional balances will help data reconciliation efforts to identify misleading field measurements.


#3 SilverShaded

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Posted 15 September 2021 - 08:46 AM

I agree with Pilesar an approach to equilibrium apporach is fine.  In terms of catalyst deactivation why model it?  Some HPU's have run for 25 years without changing catalyst (mostly because they were running at low temperature) but these catalysts do not deactivate quickly.


Edited by SilverShaded, 15 September 2021 - 08:46 AM.


#4 A_D_M_MII

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Posted 15 September 2021 - 01:09 PM

 

A few comments for consideration... 
Consider using equilibrium reactors instead of PFR. Adjust the approach to equilibrium to tune for catalyst performance. 
Are you adding excess air to your combustion? Extra air lowers flue gas temperature and affects the convection section heat transfer. The heat transfer to the reaction is in the balance also. An inaccurate heat of reaction might be affecting your results.
Including the convection section in the model will provide additional balances that have to be matched with the flue gas flow and temperatures. Adding these additional balances will help data reconciliation efforts to identify misleading field measurements.

 

OK thank you!
 
1. But, excess air could be better because of the decreases of the initial flue gas temperature at the outlet of the adiabatic combustion reactor, so for the same thermodynamic of the reaction of the reformer, the heat which is taken by the reactor is the same, and the flue gas to convection zone will be less than with a reduction of the air flow.
 
2. Heat of the reaction is given by Hysys, i can do nothing, the composition is also correct, this is the fact the made me think about the deactivation of the catalyst, but it's difficult.
 
3. Yes i know what you mean, i could verify the heat balance with the rest of the process with the convection zone.
 
Thank you again!
:rolleyes:


#5 PingPong

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Posted 15 September 2021 - 04:36 PM

It's not clear to me how your model works, but I agree with the others that you best use ATE.

 

Note also that your firebox has a heat loss that impacts the flue gas temperature entering the convection bank.

Convection bank also has some heat loss.

 

I suggest you read this topic: https://www.cheresou...-reformer-unit/

 

and in this topic I explained how to verify whether lab analysis are correct or not: http://www.cheresour...ormer-catalyst/

 

EDIT: first topic link was wrong, replaced by correct one.


Edited by PingPong, 16 September 2021 - 01:52 PM.


#6 SilverShaded

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Posted 16 September 2021 - 10:07 AM

 

 

A few comments for consideration... 
Consider using equilibrium reactors instead of PFR. Adjust the approach to equilibrium to tune for catalyst performance. 
Are you adding excess air to your combustion? Extra air lowers flue gas temperature and affects the convection section heat transfer. The heat transfer to the reaction is in the balance also. An inaccurate heat of reaction might be affecting your results.
Including the convection section in the model will provide additional balances that have to be matched with the flue gas flow and temperatures. Adding these additional balances will help data reconciliation efforts to identify misleading field measurements.

 

OK thank you!
 
1. But, excess air could be better because of the decreases of the initial flue gas temperature at the outlet of the adiabatic combustion reactor, so for the same thermodynamic of the reaction of the reformer, the heat which is taken by the reactor is the same, and the flue gas to convection zone will be less than with a reduction of the air flow.
 
2. Heat of the reaction is given by Hysys, i can do nothing, the composition is also correct, this is the fact the made me think about the deactivation of the catalyst, but it's difficult.
 
3. Yes i know what you mean, i could verify the heat balance with the rest of the process with the convection zone.
 
Thank you again!
:rolleyes:

 

Check the heat of reaction carefully, some older versions of hysy were calculating it incorrectly in some models. e.g. Gibbs reactor gave a different value to conversion reactor for the same amount of conversion.
 


Edited by SilverShaded, 17 September 2021 - 03:38 AM.


#7 PingPong

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Posted 16 September 2021 - 01:54 PM

@ A_D_M_MII

 

Note that I edited my previous post: First topic link was wrong, replaced by correct one.






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